Airway devices are widely used in hospital surgical environments to provide respiratory assistance and ventilate patents during medical procedures. While there are a multitude of airway devices currently on the market, one popular airway device is an endotracheal tube and another is a supra-glottic support device, such as a laryngeal mask airway (LMA). While the use of these devices is widespread, there are disadvantages associated with each of these devices.
Endotracheal tubes, for example, are used to ventilate patients requiring anesthesia and/or respiratory assistance. An example of a conventional endotracheal tube is a plastic tube, which is inserted into a subject's mouth, passed down the trachea through the vocal cords, and lodged in the trachea proximal (or above) the lungs. The endotracheal tube may have a cuff or balloon portion surrounding the circumference of the endotracheal tube near the distal end that rests in the subject's trachea. After the endotracheal tube has been inserted properly, the cuff may be inflated to seal against the wall of the trachea. Once sealed, positive pressure ventilation may be used to provide respiratory assistance and, if desired, anesthesia or other gas, gas mix, etc., to the patient though the endotracheal tube via a ventilator. The cuff provides a seal that tends to block liquids and solids from passing along the outside of the endotracheal tube between the tube and the trachea wall and entering the subject's lungs.
A LMA typically includes a hollow tube (sometimes referred to as a tubular guide, tube or guide) and a laryngeal mask. The laryngeal mask of the LMA is intended to fit in the mouth of a patient and to cover the two openings leading, respectively, to the esophagus and the trachea, on the one hand, and blocking the fluid path to and from the esophagus and stomach, on the other hand, thereby providing a fluid path to the trachea and lungs for ventilating the patient. The laryngeal mask may be positioned without requiring a physician to view the airway directly. The laryngeal mask has an inflatable cuff or rim area. Once the laryngeal mask is placed into the subject's mouth, the cuff can be inflated to seal against the walls of the inside of the mouth and, if positioned properly, to block flow to and from the esophagus. A flexible, membranous support material extends from the cuff to form a recessed area, e.g., a space or volume, into which a gas mix can be pumped through the tube or other instrumentality of the LMA to provide the requisite air and/or anesthesia to the patient. The tube is of relatively large diameter, as compared to the usually relatively narrower diameter passage of a conventional endotracheal tube, and such relatively large diameter facilitates gas mix and exhalant flow with relatively minimal interference, pressure drop, etc. The support material supports the cuff from the tube. Thus, the LMA can be used to supply a gas mix to the recessed area and from there to the trachea.
In patients that require ventilation with an airway device (e.g., critically ill or injured subjects), it is important to maintain a continuous airway. In such patients, if ventilation begins with a supra-glottic support device (e.g., a LMA) and intubation subsequently becomes necessary, the supra-glottic support device must be removed from the patient so that an endotracheal tube can be placed. Doing so, however, requires that the patient's airway be temporarily disrupted while also increasing the risk that the patient's airway may not be recovered. Additionally, placing an endotracheal tube requires the skill of an experienced medical professional, who may not be present in all circumstances in which unexpected intubation is required.